Fix webview-accessible resource checks in AllowCrossRendererResourceLoadHelper

extensions/browser/url_request_util.cc

Index: extensions/browser/url_request_util.cc
diff --git a/extensions/browser/url_request_util.cc b/extensions/browser/url_request_util.cc
index c7347cdbe956a4fc74d847daccf7175c1b3885d2..20e32c61b77d19208bb7ce156c7bc4a895d2415c 100644
--- a/extensions/browser/url_request_util.cc
+++ b/extensions/browser/url_request_util.cc
@@ -152,17 +152,16 @@ bool AllowCrossRendererResourceLoadHelper(bool is_guest,
                                           const std::string& resource_path,
                                           ui::PageTransition page_transition,
                                           bool* allowed) {
-  // |owner_extension == extension| needs to be checked because extension
-  // resources should only be accessible to WebViews owned by that extension.
-  if (is_guest && owner_extension == extension &&
-      WebviewInfo::IsResourceWebviewAccessible(extension, partition_id,
-                                               resource_path)) {
-    *allowed = true;
-    return true;
-  }
+  if (is_guest) {
+    // An extension's resources should only be accessible to WebViews owned by
+    // that extension.
+    if (owner_extension != extension) {

[alexmos, 2017/03/23 18:23:53]

Seems like the old check also allowed web-triggerable loads to any non-owner
extension.  Is there any case where a webview should be loading resources from
an app/extension that doesn't own it?  If we wanted to be conservative here, we
could also return false without setting *allowed for that case.  But this
stricter check doesn't break any tests either. :)

[lfg, 2017/03/23 18:49:40]

This is a bug I fixed in the past, but Paul reintroduced it here
https://codereview.chromium.org/1312653003 (PS5->PS6; shame on me for not
looking at the CL after l-g-t-m'ing it).

<webview> should only load resources specified in the manifest of the extension
that owns it.

+cc paulmeyer

+      *allowed = false;
+      return true;
+    }
 
-  if (is_guest && !ui::PageTransitionIsWebTriggerable(page_transition)) {
-    *allowed = false;
+    *allowed = WebviewInfo::IsResourceWebviewAccessible(extension, partition_id,
+                                                        resource_path);
     return true;
   }